2nd PUC Biology Answers - March 2023 Board Exam | Karnataka board - Pdf

 

PART - A

I. Answer the correct alternative from the choices below: 10 x 1 = 10

1. Which among these one is not a post-fertilization event? 

 a) Gametogenesis

2. The most resistant organic material present on exine of pollen grains is

c) Sporopollenin

3. The first movements of the foetus are observed during which month of the

pregnancy? 

c) Fifth month

4. Tassels in Corncob represent 

 d) Stigma and style

5.Which of the following sexually transmitted diseases is not completely

curable? 

(c) Genital herpes

6. An example for non-medicated IUD is 

b) Lippes loop

7.Who noted that the behaviour of Chromosomes was parallel to the behaviour

of genes? 

d) Walter Sutton & Theodore Boveri

8.The first genetic material could be

 d) RNA

9. Which of the following is used as an Industrial pollution indicator? 

 b) Lichens

10 .The disease Chikungunya is transmitted by 

b) Aedes Mosquitoes

11. Sonalika and Kalyan Sona are varieties of 

 a) Wheat

12.Which one of the following alcoholic drinks is produced without

distillation? 

a) Wine

13.Plant cells bombarded with high velocity microparticles of gold or tungsten

coated with DNA in a method known as 

b) Biolistics

14.The commonly used vector for cloning genes in animals is

 b) Disarmed retrovirus

15. According to Allen’s rule the mammals from colder climates have

 d) Shorter ears and shorter limbs

II. Fill in the blanks by choosing the appropriate word or words from those given below: 5 x 1 = 5

(food web, standing state, Gause’s- competitive exclusion principle, atmosphere, single base pair of DNA)

16. Point mutation arises due to the change in __________

Ans: Single base pair of DNA

17.________ states that two closely related species competing for the same

resources cannot co-exist indefinitely and competitively inferior one will be

eliminated eventually. 

Ans: Gause’s-competitive exclusion principle

18.The amount of nutrient, such as carbon, nitrogen, phosphorus and calcium

present in the soil at any given time is called as ________ 

Ans: Standing state

19. The reservoir of gaseous type of nutrients cycle exist in the ________

 Ans: Atmosphere

20 The natural interconnection of food chains make it a ________ 

 Ans: Food web

PART - B

III. Answer any five of the following question in 3-5 sentences each, wherever applicable: 5 x 2 = 10

21. What are hermaphrodites? Mention one example.

Ans: Animals that possess both male and female reproductive organs are called

hermaphrodite.

E.g., Earth worm /Sponge / Tape worm/ Leech (any one example)

22. Distinguish between Menstrual cycle and Oestrus cycle

Ans:

The cyclical changes in the activities of ovaries and accessory ducts as well as

hormones of primate is called menstrual cycle.

The cyclical changes in the activities of ovaries and accessory ducts as well as

hormones of non-primates is called oestrus cycle

23.Mention the four symptoms of Down’s syndrome

 Short statured with small round head

 Furrowed tongue and partially open mouth

 Palm is broad with characteristic palm crease

 Physical, psychomotor and mental development is retarded

(1⁄2 Mark each)

24. Write the genotype of the parents when their children are with A, B, AB, O

blood groups. 

Ans: The genotype of the parents blood group is IA i and IB I /IAIO and IBIO

25. Write the two basic amino acids residues which are rich in histones

 Lysine

 Arginine (1 Mark each)

26. Differentiate between Geitonogamy and Xenogamy

Ans

Transfer of pollen grains from the anther to the stigma of another flower of the

same plant is called geitonogamy.

Transfer of pollen grains from the anther to the stigma of a different plant of

the same species.

27. Mention any two examples of evolution by anthropogenic action

 Industrial melanism

 Overuse of herbicide and pesticide

 Antibiotic or drug resistance in bacteria

(Any two 1 Mark each)

28.The use of CNG is better than Petrol or Diesel. Give four reasons

 CNG burns most efficiently, unlike petrol or diesel, in the automobiles

and very little of it is left unburnt

 CNG is cheaper than petrol or diesel

 CNG cannot be siphoned off by thieves

 CNG cannot be adulterated like petrol or diesel (1⁄2 Mark each)

PART – C

IV. Answer any five of the following question in 40 – 80 words each, wherever applicable: 5 x 3 = 15

29. a) Why is oxytocin necessary for Parturition?

   b) List any four hormones secreted by Placenta

Ans:

a) Oxytocin acts on the uterine muscle and causes stronger uterine

contractions, which in turn stimulates secretion of oxytocin, this leads to

expulsion of the baby out of the uterus.

(b) Hormones secreted by Placenta

 Human Chorionic Gonadotropin /hCG

 Human Placental Lactogen /hPL

 Estrogen

 Progestogens

 Relaxin ( 1⁄2 Mark each , Any Four)

30. What is infertility? Give reasons for infertility in humans

Couples who are unable to produce children in spite of unprotected sexual co-

habitation.

Reasons;

 Physical

 Congenital

 Diseases

 Drugs

 Immunological

 Psychological

(Any four 1⁄2 Mark each)

31. Mention any three applications of DNA finger printing technique

 In forensic science

 In determining population diversities

 Evolutionary biology

 In determining genetic diversities

(Any three 1 Mark each)

32. Draw a neat labelled diagram of Miller’s experiment

Ans: Diagram in NCERT Text book

33. a) Write the infectious forms of Plasmodium which enter human body

through mosquito bite.

b) Draw a neat labelled diagram of structure of an antibody molecule

Ans: 

a) Sporozoites 

b) Diagram in NCERT Text book

34. What is Poultry? Mention two important components of poultry farm

Management.

Ans: 

Poultry is the class of domesticated fowl (birds) used for food or for their eggs

including, chicken and ducks, and sometimes turkey and geese. Important

components of poultry farm management:

• Selection of disease free and suitable breeds

• Maintenance of proper and safe farm conditions

 Providing proper feed and water

• Maintenance of hygiene and health care

(Any two 1 Mark each)

35. What is Ecological Succession? Distinguish between Primary succession and

Secondary succession

Ans:

The gradual and fairly predictable change in the species composition of a

given area is called ecological succession

• A process of succession that starts in an area where no living organisms are

there, these could be areas where no living organisms ever existed, say bare

rock is called primary succession

• A process of succession that starts in areas that somehow, lost all the living

organisms that existed there is termed secondary succession

36. a) Mention four “Evil Quartet”, which cause deletion of biodiversity.

b) Among vertebrates which group of animals has the highest number in

global biodiversity? (1⁄2 Mark for each)

Ans:

a) Four “Evil Quartet”

 Habitat loss and fragmentation

 Over-exploitation

 Alien species invasions

 Co-extinctions

b) Fishes

PART – D

V. Answer any three of the following questions in about 200 – 250 words each, wherever applicable: 3 * 5 = 15

37. What is double fertilization? Describe fertilized embryo sac with a neat labelled diagram

Ans:

The phenomenon of two types of fusions i.e., syngamy and triple fusion that take place in an

embryo sac of flowering plants is termed double fertilisation. Structure of fertilized embryo sac:

• The fertilized embryo sac consist large primary

endosperm cell consisting triploid primary

endosperm nucleus.

• It also consists of diploid zygote.

• At chalazal end it consist degenerating antipodal

cells and at micropylar end it has degenerating

synergids.

38. Draw a neat labelled diagram of human sperm

Ans: Diagram in NCERT Text book

1⁄2 Mark For each labelling   1 mark for Diagram

39. What is incomplete dominance? Explain it with reference to flower colour in

snapdragon.

Ans: 

A phenomenon where both the alleles of a character express incompletely

producing a new intermediate phenotype in the heterozygous condition is

called incomplete or partial dominance or blended inheritance.

Correns crossed homozygous red flowered plant (RR) with homozygous white

flowered plant (rr), surprisingly in F1

generation all hybrids were pink flowered

plants (Rr).

The dominant allele ‘R’ was not completely

dominant over the recessive allele ‘r’ and this

made it possible to distinguish Rr as pink from

RR (red) and rr (white)

When F1 pink flowering plants were self-

crossed, the F2 generation produce 25% red

flowered plants, 50% pink flowered plants and

25% white flowered plants in 1:2:1 ratio.

From the hybridisation results we can observe

that F2 phenotypic & genotypic ratio in

incomplete dominance are same i.e., 1 : 2 : 1.

1 homozygous red, 2 heterozygous pink and 1 homozygous white.

(Note: Schematic representation can also be considered for Two

Marks and Explanation for Two Marks)

40. Explain five benefits of creating Transgenic animals

Ans:

 Normal physiology and development: Transgenic animals can be

specifically designed to allow the study of how genes are regulated,

and how they affect the normal functions of the body and its

development.

 Study of disease: Many transgenic animals are designed to increase

our understanding of how genes contribute to the development of

disease. These are specially made to serve as models for human

diseases so that investigation of new treatments for diseases is made

possible.

 Biological products: Transgenic animals that produce useful biological

products can be created by the introduction of the portion of DNA (or

genes) which codes for a particular product such as human protein

used to treat emphysema (α-1- antitrypsin), phenylketonuria (PKU)

and cystic fibrosis. human protein-enriched milk alpha-lactalbumin

 Vaccine safety: Transgenic mice are being developed for use in testing

the safety of vaccines before they are used on humans. Transgenic mice

are being used to test the safety of the polio vaccine.

 Chemical safety testing: This is known as toxicity/safety testing. The

procedure is the same as that used for testing toxicity of drugs.

Transgenic animals are made that carry genes which make them more

sensitive to toxic substances than non-transgenic animals. Toxicity

testing in such animals will allow us to obtain results in less time.



Note: Mentioning only value points without explanation 1⁄2 Mark each

41. Name the disease caused by following organisms:

a) Entamoeba histolytica

b) Epidermophyton

c) Salmonella typhi

d) Wuchereria malayi

e) Plasmodium vivax

Ans: 

a) Amoebiasis/Amoebic dysentery 

b) Ringworm

c) Typhoid

d) Filariasis/Elephantiasis

e) Malaria

42.Name the technology that can successfully increase the herd size of cattle in a

short time and explain the steps involved in this technology.

Ans: 

Multiple Ovulation Embryo Transfer Technology (MOET) is one programme

for herd improvement.

 In this method, a cow is administered hormones, with FSH-like

activity, to induce follicular maturation and super ovulation – instead

of one egg, which they normally yield per cycle, they produce 6-8 eggs.

 The animal is either mated with an elite bull or artificially inseminated.

 The fertilised eggs at 8–32 cells stages, are recovered non-surgically

and transferred to surrogate mothers.

 The genetic mother is available for another round of super ovulation.

 This technology has been demonstrated for cattle, sheep, rabbits,

buffaloes, mares, etc. High milk-yielding breeds of females and high

quality (lean meat with less lipid) meat-yielding bulls have been bred

successfully to increase herd size in a short time.

VI. Answer any two of the following questions in about 200 – 250 words each, wherever applicable: 2 *5 = 10

43.Explain the role of microbes in industrial products.

Ans: 

Production of microbial products useful to human beings on an industrial

scale requires growing microbes in very large vessels called fermentors.

Aspergillus niger - citric acid

Acetobacter aceti - acetic acid

Clostridium butylicum - butyric acid

Lactobacillus -lactic acid.

Yeast (Saccharomyces cerevisiae) - ethanol.

Penicillium notatum – Penicillin

Streptococcus - Streptokinase

Trichoderma polysporum - Cyclosporin A

Monascus purpureus - Statins

(Any Five - Microbes and its product – Each One Mark)

44. a) Write any four tools used in recombinant DNA technology.

b) Mention any two methods of introducing alien DNA into host cells.

c) Name the stain used to visualize DNA fragments in Gel electrophoresis.

Ans: 

a) Tools used in recombinant technology:

 Enzymes,

 Vectors and the

 Host organism

 Bioreactors

b) Methods followed to introduce alien DNA into host cells:

 Microinjection

 Biolistic method/gene gun

 Vector mediated

 Heat Shock

 Disarmed pathogen vectors                        (Any two 1 Mark each)

c) Ethidium bromide .

45. Describe Fredrick Griffith experiment to show transformation in Bacteria.

Ans: 

 Mice infected with the S strain of Streptococcus pneumoniae (virulent)

died from pneumonia infection but

 Mice infected with the R strain did not develop pneumonia and were

alive.

 Mice infected with heat -killed S strain bacteria did not kill them and

mice were alive.

 When he injected a mixture of heat-killed S strain and live R strain

bacteria, the mice died. Moreover, he recovered living S bacteria from

the dead mice.

 He concluded that the R strain bacteria had somehow been

transformed by the heat-killed S strain bacteria.

 Some ‘transforming principle’, transferred from the heat-killed S strain,

had enabled the R strain to synthesise a smooth polysaccharide coat

and become virulent.

 This must be due to the transfer of the genetic material.

46.a) Mention any two mechanisms how human body compensates low oxygen

availability at higher altitude.

b) Write two suspended activities in animals against abiotic stresses with

suitable examples.

c) The Abingdon tortoise in Galapagos Islands became extinct after goats

were introduced on the Island. Mention the type of interaction.

Ans:

a) The body compensates low oxygen availability by increasing red blood cell

production,

Decreasing the binding affinity of haemoglobin and by increasing breathing

rate.

b) * Bears going into hibernation during winter to escape in time.

* Snails and fish go into aestivation to avoid summer–related problems-

heat and desiccation.

* Zooplanktons – Diapause. (Any two 1 Mark each)

c) Competition/Competitive Exclusion.

47. Write a brief account of electrostatic precipitator with a neat labelled

diagram.

Ans:

 The electrostatic precipitator can remove over 99 per cent particulate

matter present in the exhaust from a thermal power plant.

 It has electrode wires that are maintained at several thousand volts,

which produce a corona that

releases electrons.

 These electrons attach to dust

particles giving them a net

negative charge.

 The collecting plates are

grounded and attract the

charged dust particles.

 The velocity of air between

the plates must be low enough to allow the dust to fall. 

Diagram in NCERT Text book

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